Patent GB-205864-A (GB)
Abstract: 205,864. Coventry Automatic Telephones, Ltd., (McBerty, F. R., and Arter, R. C.). July 21, 1922. Automatic and semi-automatic exchange systems.-An operator is provided with a two-way connecting-circuit, either end of which may be connected through relays or other switching devices to a selector which extends the call to the wanted line. Lamps are provided for indicating the identity of both the lines connected to the connecting-circuit. The operator can restore the connections at both ends of the connecting-circuit or can hold one end and restore the other. The Figures should be arranged with Fig. 2 above Fig. 1, Figs. 3 and 4 to the right of Figs. 1 and 2 respectively, and Fig. 5 above Fig. 2. In the system described, a toll operator at the exchange shown in Fig. 1 can extend a two-way connecting- circuit A by tens and units relays 120, 130 controlled by keys K to toll lines, such as 101, 102, incoming from a distant exchange X and can extend the call over tens and units relays 150, 160, also controlled by keys K, to a toll line 300, 302 leading to a distant exchange Y, Fig. 3. The toll operator may also extend a call from a distant exchange, such as X, to a subscriber's line on a local exchange Z, Fig. 4. To do this, she connects the left-hand end of circuit A to the incoming trunk 101, 102 from exchange X as before, and, by depressing appropriate keys K to energize relays 150a, 160a, Fig. 2, extends the right-hand end of circuit A to a trunk 400, 402 which is extended to the called line by selectors 451, 461, 471 of ordinary type under control of the toll-operator's sending equipment (for local calls) and keyboard shown in Fig. 5. A call from the distant exchange Y can be similarly extended to a local-exchange line by connecting the righthand end of circuit A as before to trunk 300, 302 and the left-hand end over relays 120a, 130a, Fig. 2, to the local exchange trunk 400, 402. Calls from local lines can also be extended to toll lines. Connection of calling line 100 to connecting circuit A. A line 100 on exchange X is extended through jack J to toll line 101, 102, the operator at exchange X sending ringing-current through relay 103 to energize a self-locking relay 105 and light the call lamp 106. The toll operator moves the key 170 of an idle connecting-circuit A to the left, energizing a relay 110 which connects the keys K to the magnets such as 120, 120a, 130, 130a adapted to extend the left-hand end of circuit A. The toll operator depresses the keys K necessary to extend circuit A to the line indicated by the lamp 106, energizing in this case magnets 120, 130, which lock up over their first contacts. A relay 119 in the locking-circuit of magnet 120 lights lamp 182 over the contact of a relay 175 energized in series with a cut-off relay 104. Connection to toll line 300, 302 to distant exchange. The toll operator enquires the connection desired, moves key 170 to the right to energize relay 140 and depresses keys K appropriate to energize tens and units magnets 150, 160 (over the contacts of relay 140) to extend circuit A to the line 300, 302. The magnets 150, 160 lock up, energizing a relay 181 which substitutes lamp 183 for lamp 182, the glowing of lamp 183 indicating a through connection from one toll line to another. Relay 178 energizes in series with a relay 304, lighting a lamp 309 to indicate to the toll operator that line 300, 302 is in use. Release. Clearing signals are given by the operators at exchanges X, Y sending ringing- current to energize relays 176, 177, controlling a relay 180 which causes a slow-acting interrupter relay 179 to flash the lamp 183. The toll operator releases the connection by depressing key 174 which opens the holding-circuits of all the magnets such as 120, 150. She may, however, hold one end of the connection by moving key 170 to the left or to the right, thereby closing a fresh holding-circuit for the magnet 120 or 150. Lamp signals indicating identity of toll lines. Lamps L1 - - L6, Fig. 1, individual to the toll lines are connected to the contacts of magnets 120, 130 &c. in such a way that the operator may, at any time during a connection, identify the incoming or outgoing line by moving the key 170 to the left or right. Connection of calling toll line to local line. A line 100 on exchange X is connected to an idle connecting circuit at the toll exchange as before, and the toll operator moves key 170 to the right to energize relay 140 and depresses keys K appropriate to energize magnets 150a, 160a, Fig. 2, to extend circuit A to a local selector trunk 400, 402. The locking-circuits of magnets 150a, 160a do not include relay 181 so that the lamp 182 remains lit, indicating that a toll connection is being established with a local line. A relay 406, Fig. 4, lights lamp 403 to mark the trunk 400, 402 busy, and closes a circuit through relay 405 and leads 402, 213, contacts of key 172a (depressed by the toll operator), leads 207, 502, and relay 504 at the operator's local equipment. Relay 504 lights the lamps 505, 506. Toll operator's keyboard equipment for local calls, Fig. 5. This comprises rows of keys III, IV, V for controlling the selector and connector, row I for party-line selection, and two keys 9 and 0 in row II for special purposes. The register switch 512, 513 is stepped round by magnet 510 in unison with the selectors until the wiper 512 reaches a contact connected to a depressed key, whereupon the sequence switch 522, 523, 524 controlled by magnet 520 is moved on to cause the change-over at the selector. Relays 507, 508, 509 control an out-of-order lamp 534, which lights up if the register switch fails to operate properly. Control of group selector, Fig. 4. The toll operator depresses keys in rows I, III, IV, V according to the line wanted, the key O in row II for ordinary calls, and a starting key 540. Relay 503 energizes and (1) cuts off relay 504 and lamp 505, (2) closes a fresh circuit for the guard lamp 506, and (3) closes a circuit over wiper 523 to move the sequence switch into its second position. A relay 514 is then energized over the special key 0 in row II and closes circuits for magnets 510, 520 which move the sequence switch and register switch another step. The magnet 510 now energizes over wipers 513, 523 and closes a circuit for relay 511 which opens the circuit of magnet 510. The magnet 510 and relay 511 thus energize alternately, stepping round the register wipers 512, 513. Just before wiper 512 reaches normal, it causes relay 509 to energize magnet 520 to move the sequence switch into its 4th position, in which a selection-controlling circuit is closed through relay 514, wiper 522, leads 500, 208, key 172a, leads 215, 400, front contacts of relay 405, and relay 416 to earth. Relay 416 energizes the rotary magnet 440 which causes relay 421 to interrupt the selection-controlling circuit. The relays 514, 416 are thus intermittently energized, causing the magnets 440, 510 to act in unison. When the wiper 512 reaches a contact connected to the depressed key in row III, the magnet 520 energizes over wipers 512, 523 and moves the sequence switch into position 5, thereby opening the selection-controlling circuit so that relay 416 disconnects the rotary magnet 440. In position 5 of the sequence switch, the magnet 510 is intermittently energized and moves the wipers 512, 513 on to normal, whereupon the sequence switch moves into its 6th position in which tens selection is controlled by the tens keys. When the selection-controlling circuit is opened, relay 412 causes a self-locking relay 410 to energize the vertical magnet 430, which, by means of relay 421, interrupts its own circuit and the locking circuit of relay 410. When an idle trunk is found, relay 410 de-energizes and the call is extended over contacts of relays 405, 417 to the next selector, which is operated in a similar manner. Connection of calling toll line to special lines at local exchange. The tenth level of the first selectors is wired to special second selectors which connect directly to special trunks, such as those to information operators. These trunks are numbered 95 - - 99 and are selected by depressing key 9 in row II and one of the keys 5 - - 9 in row III, each of these also operating a contact, 532 to energize a release relay 531. As the key 0 in row II is not depressed for these special calls, the selection-controlling circuit is closed in position 2 of the sequence switch over relay 514, wiper 522, normal contact of key O in row II, and lead 500 as before, so that the first selector is controlled by key 9 in row II. The second selector is controlled by the depressed key in row III and the sequence switch is then restored by the relay 531. Disconnection of operator's equipment. When the wiper 523 engages its last contact, the release relay 530 closes a circuit over lead 501 for relay 221, Fig. 2, which causes relay 220 to disconnect the sending equipment from the trunk 400, 402. Clearing signals. When the called subscriber hangs up, relay 408 de-energizes and causes relay 404 to bridge a battery and retardation coils across the trunk 400, 402, energizing relay 177, Fig. 1, which causes relay 180 to energize the interrupter relay 179 to flash the lamp 182. The connection is released as described above. Connection of calling local line 490, Fig. 4, to called toll line. A calling line 490 is extended to a local auto-manual operator who operates a selector 395, Fig. 3, to select an idle trunk to the toll operator's position, thereby lighting lamp 309a. The toll operator connects to this trunk by relays 120b, 130b controlled by keys K as before.